CrSi (Ni, Al) Thin Film Electrical Stability And Corrosion Behavior In The Acidic Environment Of The Medium

Cr-Si silicide films were widely used as thin film resistors in integrated circuits (ICs) and microelectronics industry, due to high sheet resistance, low temperature coefficient of resistance (TCR), high thermal stability, good long-term reliability and chemical stability. In this paper, Cr-Si-Ni and Cr-Si-Ni-Al films were prepared on Al₂O₃ substrates by magnetron sputtering system using alloy targets of Cr₁₇Si₈₀Ni₃ and Cr₁₆Si₇₄Ni₃Al₇, respectively. The electrical stability and corrosion mechanism of two types of the films annealed in Ar were investigated in the simulated acidic environments (HCl, H₂SO₄ and HNO₃ solution). The method of the relative resistance change (â–³R/R) was used to evaluate the electrical stability and the corrosion resistance of the film in the corrosion solution environments. Analysis of the surface components and depth profiles of the corroded thin films was performed by Auger electron spectroscopy (AES). The surface morphology of the films after corrosion was examined in a scanning electron microscopy (SEM).The relative resistance change trend of the nanocrystalline Cr-Si-Ni films by annealing was similar when the films immersed in the different acid solution (HCl, H₂SO₄ and HNO₃ solutions): the value of the relative resistance change of the films was continuous increased with the immersion time increased. Furthermore, with the increase of the solution concentration and temperature, the value of the relative resistance change of the films was also increased. The results show that the films had the better the electrical stability and the corrosion resistance in the lower temperature and concentration solution. However, the electrical stability of the films was decreased with the increase of the solution concentration and temperature. The relative resistance change trend of the nanocrystalline Cr-Si-Ni-Al films by annealing was the similar to the Cr-Si-Ni films when the films immersed in the different acid solution. The films possessed the better electrical stability and corrosion resistance in the lower temperature and concentration solution. With the increase of the solution concentration and temperature, the electrical stability of the films was decreased.The microstructure of the Cr-Si-Ni films played a major role in its corrosion resistance in the different acid solutions. The nanocrystalline Cr-Si-Ni films by annealing present a spontaneous trend to passivation in the different acid solutions. The AES results showed that the surface of the films can form a stable SiO₂ protective layer to protect the films from further corrosion in three acid solutions which improve the corrosion resistance. However, the passive layer could not form and protects the inner film with the increase of the temperature and concentration, and the electrical stability and the corrosion resistance of the films was decreased.The addition of Al into Cr-Si-Ni films improves its electrical stability and the long-term corrosion resistance obviously, especially in the high temperature and concentration HNO₃ and H₂SO₄ solutions. A stable mixed oxide protective layer formed on the surface of the Cr-Si-Ni-Al films, where the dominant compound of the passive film was Al₂O₃ and SiO₂. As a result, the electrical stability and the corrosion resistance of the films was increased.Compared with the value of the relative resistance change of the Cr-Si-Ni and Cr-Si-Ni-Al films immersed in HC1, H₂SO₄ and HNO₃ solutions, two types of the films immersed in the HC1 solution exhibited the best electrical properties. It indicated that electrical stability and the corrosion resistance of two types of the films decreased as HCI solution, HNO₃ solution, and H₂SO₄ solution in sequence.